COMPARISON OF A UNIPOLAR DEFIBRILLATION SYSTEM WITH A DUAL LEAD SYSTEM USING AN ENLARGED DEFIBRILLATION ANODE

The unipolar system for transvenous defibrillation, consisting of a si ngle right ventricular lead as the cathode and the device shell as ano de, has been shown to combine low defibrillation thresholds (DFTs) and simple implantation techniques. We compared the defibrillation effica cy of this system with the defibrillation efficacy of a dual lead syst em with a 12-cm long defibrillation anode placed in the left subclavia n vein. The data of 38 consecutive patients were retrospectively analy zed. The implantation of an active can system wets attempted in 20 pat ients (group 1), and of the dual lead system in 18 patients (group 2). Both groups had comparable demographic data, cardiac disease, ventric ular function, or clinical arrhythmia. The criterion for successful im plantation was a DFT of less than or equal to 24 J. This criterion was met in all 18 patients of group 2. The active can system could not be inserted in 3 of the 20 group 1 patients because of a DFT > 24 J. In these patients, the implantation of one (n = 2) or two (n = 2) additio nal transvenous leads was necessary to achieve a DFT less than or equa l to 24 J. The DFTs of the 17 successfully implanted group 1 patients were not significantly different from the 18 patients in group 2 (12.3 +/- 5.7 J vs 10.8 +/- 4.8 J). The defibrillation impedance was simila r in both groups (50.1 +/- 6.1 Omega vs 48.9 +/- 5.2 Omega). In group 1, both operation duration (66.8 +/- 17 min vs 80.8 +/- 11 min; P < 0. 05) and fluoroscopy time (3.3 +/- 2.1 min vs 5.7 +/- 2.9 min; P < 0.05 ) were significantly shorter. Thus, the active can system allows relia ble transvenous defibrillation and a marked reduction of operation dur ation and fluoroscopy time. The dual lead system, with an increased su rface area defibrillation anode, seems to be a promising alternative f or active can failures.